Firearm



B. TSCHOEPE Dec. 3l', `1968 FIREARM Filed Aug. 26. 1966 ,//AHJ ZZ//Q////f//fa FEED, aREEcH EJECTION MECHANISMS, ETC.

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INVENTOR BRUNO TSCHOEPE QQ/LAE@ ATTORNEYS United States Patent O 3,418,741 FIREARM Bruno Tschoepe, Karlsruhe-Durlach, Germany, assignor to Dynamit Nobel Aktiengesellschaft, Troisdorf,

Germany Filed Aug. 26, 1966, Ser. No. 575,325 Claims priority, application Germany, Sept. 8, 1965,

3 claims. (di. 42-77) ABSTRACT OF THE DISCLOSURE Background of the invention The automatic function of semi-automatic and fully automatic firearms depends, as is known, on the weight and on the resistance to the pressing-through or forcingthrough of the bullet to be fired as well as on the weight and on the `force of the breech closing spring of the breech mechanism. Correspondingly, it is obvious that vduring the firing of bullets of the same caliber but with very considerable weight differences from one and the same arm, repercussions will arise with respect to the automatic function thereof.

This was confirmed with the test to fire from a fully automatic arms of a 9 mm. caliber both a live cartridge with a bullet of 8 grams weight as well as a practice -`.cartridge with a short-range bullet of thermoplastic material and of only 0.42 gram weight. Whereas with the normal bullet of the live cartridge a completely satisfactory fully automatic function of the arm or weapon was achieved, such a completely satisfactory fully automatic function could no longer be realized with the lightweight bullet of the practice ammunition.

Attempts to assure by changing the breech mechanism and/ or the breech closing spring, a fully automatic function of the arm also during the firing of the light-weight bullet, showed no satisfactory results as the cartridge cases were ejected from time to time only weakly and in particular as the -breech mechanism during firing of single shots did not 4catch or latch in any case, i.e., in no case was the breech mechanism caught and retained in its rearward position by the latching lever provided therefor. Also the attempt to achieve the automatic function of the arm during the firing of the light weight bullets by increasing the charge and therewith increasing the -gas pressure proved unsuccessful because the spatial prerequisites did not exist for the accommodation of a sufficiently large charge.

Summary f the invention In solution to the underlying problem to enable the firing from a semior fully automatic arm with the assurance of the automatic function thereof, both live arnmunition as well as practice ammunition of identical dimensions with a light-weight bullet of thermoplastic material, a new approach is pursued according to the present invention, which starts with the known lfact that thermoplastic materials may be elastically defromed Within certain limits by the application of pressure, and more particularly maybe deformed the more the higher the applied pressure. By reason of this property of the thermoplastic material, for example, a plastic body of predetermined cross section can be pressed or forced through an aperture correspondingly smaller in cross section by the application of a correspondingly high pressure and under elastic deformation. It follows inversely that by a corresponding dimension of the internal cross section of the aperture in relation to the cross section of the plastic body the pressure necessary for the forcing of the plastic body through the aperture can be determined at the desired magnitude. The present invention makes use of this fact in that there is provided for the firearm an interchangeable barrel for the firing of the practice ammunition, interchangeable for the barrel of normal caliber `for the firing of the live ammunition, whose bore is constructed of undersized caliber for achieving the pressing-through resistance of the bullet necessary for the automatic function of the arm or gun.

Insofar as spatial conditions permit and to the extent that it is of use, provision may additionally be made to slightly increase the charge of the cartridge. Especially by the measure of a possible increase of the charge, an inlluence may ybe exercised in a limited manner on the cross-sectional ratio between bullet and bore of the practice barrel necessary for the requisite pressing-through resistance.

The cross-sectional ratio, which differs from case to case and which inter alia, is influenced by or depends from the bullet caliber, from the type of thermoplastic material utilized for the practice ammunition, from the intended bullet range and in connection therewith from the bullet weight, from the weight and the breech closing spring force of the .breech mechanism, etc. may be determined relatively easily, possibly experimentally, for the existing conditions existing in a given case. For example, it was possible to determine experimentally that with the aforementioned plastic bullet having a weight of 0.42 gram, a completely satisfactory automatic functioning of the firearm could be achieved lif the barrel caliber was reduced from 9 mm. to 7.5 mm. and the charge was slightly increased. The cases were ejected in every instance completely satisfactory and a latching of the breech mechanism was realized during single shot firing.

Of course, the undersized caliber barrel may also be rigidly installed into a firearm that is provided exclusively for firing practice ammunition, In that case the measures according to the present invention entail, in addition to safeguarding the automatic function of the arm, additionally the advantage that all of the remaining parts of the rearm or gun can be constructed identical with a corresponding firearm or gun for the firing of live ammunition whereby the manufacture of the practice arm is considerably simplified and the cost thereof reduced.

Accordingly, it is an object of the present invention to provide a rearm which avoids by extremely simple and operationally satisfactory means the aforementioned shortcomings and drawbacks encountered with the .prior art constructions.

Another object of the present invention resides in a fully automatic or semi-automatic firearm which can be utilized for firing practice ammunition without endangering the fully automatic or semi-automatic operation thereof even when utilizing the firearm for single shot firing.

A further object of the present invention resides in a firearm that is relatively inexpensive in manufacture and assembly yet permits the use of practice ammunition consisting of thermoplastic material bullets of relatively light weight without jeopardizing the correct automatic or semi-automatic functioning of the firearm.

A further object of the present invention resides in a firearm for use with practice ammunition consisting of bullets made of thermoplastic material in which the basic parts of the firearm including the semi-automatic or fully automatic firing and breech mechanisms are identical with those used in the same firearm for firing live ammunition yet can be manufactured in a simple manner and without excessive cost.

Brief description of the drawing These and further objects, features, and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, one embodiment in accordance with the present invention, and wherein:

FIGURE l illustrates schematically a firearm provided with an interchangeable barrel for live ammunition; and

FIGURE 2 ilustrates schematically a firearm provided with an interchangeable barrel for practice ammunition.

Detailed description ofthe drawing Referring 4now to FIGURE l of the drawing, reference numeral 10 generally designates therein a conventional semi-automatic or fully automatic gun or firearm of conventional construction including a conventional feed, ejection and breech mechanisms, etc. and a barrel 11 for the firing of normal live ammunition detachably secured in a co-nventional manner. The barrel 1l has a bore with a diameter d corresponding to the caliber of the live ammunition 12. A substitute barrel 1l for the firing of practice ammunition is shown in FIGURE 2 as having a |bullet 13 of thermoplastic material and may be selectively interchanged for barrel 11. The barrel l1 thereby has a bore with a diameter d-x, whereby the reduction x is so selected as to produce the necessary resistance to a forcing or pressing through of the thermoplastic bullet as is required for producing the necessary pressure to actuate the semi-automatic or automatic means of the gun. Since all parts of the gun are of conventional construction, known per se in the art, a detailed description thereof is dispensed with herein.

While I have shown and described only one embodiment in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications as known to a person skilled in the art, and I therefore do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

I claim:

l. A firearm having automatic gas actuated recoil mechanisms and a barrel having a cartridge chamber for receiving and detonating a cartridge having a projectile of the same fixed caliber, in combination with the improvement comprising the barrel having a projectile guiding bore with a cartridge chamber end of substantially less than said fixed caliber.

2. The firearm according to claim 1, wherein said barrel bore is of substantially uniform diameter throughout its entire extent and is provided with inwardly extending rifiing ridges.

3. The method of modifying a gas pressure actuated firearm and selectively firing therefrom either conventional live ammunition or practice ammunition of the same caliber projectile, wherein the projectile of the practice ammunition consists of a readily deformable material having plastic characteristics, the firearm having interchangeable barrel capabilities with at least one barrel being characterized as being conventional for firing the live ammunition and at least one barrel having a conventional caliber cartridge chamber and an undersized bore for firing the practice ammunition, comprising the steps of removing, interchanging and assembling either the conventional barrel for the practice barrel or vice versa in the firearm `and discharging a projectile therefrom corresponding in character to the characteristics of the particular assembled barrel.

References Cited UNITED STATES PATENTS 660,496 10/1900 Evans 42--76 2,742,821 4/1956 Sweetman 42-76 3,326,133 6/1967 Stadler et al, l02-92.7

FOREIGN PATENTS 756,432 6/1933 France.

BENJAMIN A. BORCHELT, Primary Examiner. 

